[bleair]

They are fun / nice-colors to use, but be aware that your writing can disappear over time.

A friend has journals a few years old and on the right 2/3rds of the pages the writing is nearly gone (theory being maybe that side got warmer, but not certain)

[fma]

I was introduced to FriXion pens because I have a Rocketbook. I have a pack of colors. One day my daughter came out of my office with a nice drawing (she's 5...so it's more sentimental than artistic). My wife wanted me to laminate it...well...out came a blank piece of paper, except for the parts she used a regular pen.

[ExtraE]

As others are saying, try putting it in the freezer.

[neonnoodle]

Try putting the notebook in the refrigerator or freezer for a few minutes.

[jbay808]

Unfortunately, this also brings back anything you deliberately erased, which might still render some writing unreadable!

[aaronius]

This helped me when I was using them some years back during my university time. Managed to place some papers on a heater and the ink disappeared. Putting it in the freezer for a bit made it all come back.

[huhtenberg]

That's a very fair warning.

In a similar vein - I had recipes disappear from a notepad because it sat too close to the oven. Also printing on a paper that has something written on it with Frixion with cause these scribbles disappear without a trace.

Extreme temperature sensitivity of Frixion is a very good rake.

[rahimnathwani]

"printing on a paper that has something written on it with Frixion with cause these scribbles disappear without a trace"

Presumably a laser printer, which heats the paper to fix the toner.

Not sure an ink jet or dot matrix printer would do the same :)

[GeckoEidechse]

As others have already mentioned, the process is interestingly enough reversible (to some degree) by simply subjecting it to a colder environment like a freezer for a bit.

[rhinoceraptor]

I remember reading a story of a student who wrote an essay with one, which was erased because the teacher left their bag with the papers in a hot car while grading them.